Researchers have developed a new electrolyte that raises the efficiency of the zinc batteries to nearly 100%.
Every battery has two electrodes—the anode, from which electrons flow out into an external circuit, and the cathode, which acquires electrons from the external circuit—and the electrolyte, the chemical medium that separates the electrodes and allows the flow of ions between them. But researchers believe that zinc metal batteries are one of the leading candidate technologies for large-scale energy storage.
Researchers from Oregon State University have developed a new electrolyte that raises the efficiency of the zinc metal anode in zinc batteries to nearly 100%, a breakthrough on the way to an alternative to lithium-ion batteries for large-scale energy storage.
“The breakthrough represents a significant advancement toward making zinc metal batteries more accessible to consumers,” said Xiulei “David” Ji of the OSU College of Science. “These batteries are essential for the installation of additional solar and wind farms. In addition, they offer a secure and efficient solution for home energy storage, as well as energy storage modules for communities that are vulnerable to natural disasters.”
Zinc-based batteries are energy dense and seen as a possible alternative for grid energy storage to widely used lithium-ion batteries, whose production relies on shrinking supplies of rare metals such as cobalt and nickel. Cobalt and nickel are also toxic and can contaminate ecosystems and water sources if they leach out of landfills.
The cost of electricity delivered by a storage facility consisting of zinc batteries can only be competitive with fossil-fuel-produced electricity if the battery has a long cycle life of thousands of cycles. However, to this date, the cycle life has been limited by the poor reversibility performance of the zinc anode. During charging, zinc cations in the electrolyte gain electrons and get plated on the anode surface. During discharge, the plated anode gives up electrons for the workload by being dissolved into the electrolyte.
The primary challenge with zinc batteries is that zinc reacts with water in the electrolyte to generate hydrogen gas in what is called a hydrogen evolution reaction. This parasitic reaction causes a short cycle life and is also a potential safety hazard. The new electrolyte enables a coulombic efficiency (CE) of 99.95%.
Reference : Heng Jiang et al, Chloride electrolyte enabled practical zinc metal battery with a near-unity Coulombic efficiency, Nature Sustainability (2023). DOI: 10.1038/s41893-023-01092-x